Amperometric response of mediating layers on electrode surfaces to Gaussian concentration profiles in flowing streams

A model for a layer, containing catalytic centers, coated on an electrode and used for the mediation of analyte in a flowing stream is proposed and solved. The model applies to a situation of a Gaussian concentration profile of analyte impinging on the outer edge of the mediating layer. It was found that the important parameters that limit the current magnitude are the diffusion coefficient of the analyte through the layer, the effective electron diffusion coefficient through the layer and the rate of reaction between the mediator and the analyte. On evaluation of literature data, it was found that layers, high catalyst loading and with high rates of electron exchange, lead to linear peak current height versus concentration plots.